Plug-in contact assembly for printed circuit boards



an. 18, 1966 w. T. JENSEN Em 3,230, 93

PLUG-IN CONTACT ASSEMBLY FOR PRINTED CIRCUIT BOARDS Filed June '2, 1963 2 13'3 mum/WWW INVENTORS W/LL/AM [JENSEN EDWIN E GEHRT BYM M M 1M ATTORNEYS United States Patent 3,230,493 PLUG-IN CONTACT ASSEMBLY FQR PRINTED CIRCUIT BOARDS William T. Jensen, Libertyville, and Edwin E. Gehrt,

Melrose Park, Ill., assignors to Mcthode Electronics,

Inc., Chicago, 111., a corporation of Illinois Filed June 7, 1963, Ser. No. 286,397 Claims. (Cl. 33917) This invention is concerned with an electrical contact assembly of the type for making a quick-detachable connection with other contacts arranged in a second assembly.

In particulan'the invention is concerned with an assembly of a plurality of contacts on an insulating bar to hold'the contacts in properly spaced relation while other portions of the contacts are being attached in proper relation with a furthersupporting member, such as a printed circuit board.

' Theinvention is especially useful in the mounting of an assembly of contacts upon an edge portion of a printed circuit board or panel, in arrangements of the type shown in US. patent to Blain 2,946,976.

I The invention uses plug-in type of contacts in which each contact piece is formed from flat sheet metal stock and comprises a body portion having a prong portion extending forwardly from one end thereof, a suitable tab or tabs extending outwardly from one side edge of the body portion and being anchored in holes formed in the printed circuit board, so that the prong portion of the contact piece extends parallel with the face of the board and is spaced away from the board. Alternate contact pieces in the assembly constituting a first set of contacts are arranged in a row parallel with the face of the board, and the remaining contact pieces interposed between adjacent pairs of the first set of contact pieces being arranged in a second row parallel with the first row of contact pieces but spaced further from the face of the board than the first set.

One object of the invention is to provide an insulating support bar for engaging the outer edge of both sets of contact pieces and maintaining them in proper spaced relation, both before the'mounting of the assembly on the printed circuit board and after such mounting.

A further object of the invention is to provide at least one tab on the outer edge of the body portion of each contact piece, the tab passing through a hole formed in the supporting bar and being shaped to efiectively hold the contact piece in position on the bar.

A preferred embodiment of the invention is illustrated in the accornpanyihgdrawing in which:

FIGURE 1 is a'view of the outer face of a contactsupporting bar showing aplurality of contact pieces supported thereon;

' FIGURE 2 is a sectional view of FIGURE 1 taken along the cutting plane 2-2;

FIGURE 3 is a view of FIGURE 1 as seen from the side of FIGURE 1; and FIGURE 4 is a sectional view of FIGURE 3 taken along the cutting plane 4-4.

All of FIGURES 14 are shown on an enlarged scale with respect to the actual dimensions used in practice.

The contact assembly involves a supporting bar 2 formed of insulating material, and preferably formed by molding from a plastic state. As shown in FIGURE 2, the bar 2 is of rectangular section having a rear face 2a, top and bottom faces 2b and 2c and a front face 2d which is provided with a shallow groove 2d extending throughout the length of the bar and located centrally of the front face. The bar 2 is provided with a plurality of transverse slots 2e formed through the rear face 201 and extending forwardly to the plane 2 see FIGURES ice 2 and 4. These slots 22 are equally spaced along the length of the bar 2 and form sockets for receiving the body portions of the flat contact pieces to be mounted on the bar. Each slot has an aperture 2e extending through the remaining sectional portion of the bar and opening into the groove 2d. The apertures for adjacent slots are displaced on opposite sides of the center of the groove 2d.

The contact pieces carried by bar 2 are formed from sheet metal stock by punching and coining operations in the manner disclosed in copending application of Gehrt et al. Ser. No. 381,285 filed June 25, 1964, which is a cont-inuation-in-part of Ser. No. 96,947 filed March 20, 1961 now abandoned. It is preferred that the contact tongues of the contact pieces shall be of the forked or split-tongue type in which the facing edges of the two tines or prongs are rounded to conform generally with a cylindrical surface. However, in the broader aspect of the invention the contact tongues need not be of the forked type.

The contact pieces may all be of the same construction, but in the arrangement illustrated in the drawing, alternate pieces marked by the numeral 3 in FIGURE 1 are constructed to provide a first row A of split-prong contacts 3a indicated in FIGURE 2 as spaced somewhat in front of the printed circuit board PCB, and the remaining contact pieces marked 3 in FIGURE 1 are of somewhat different construction to provide a second row B of split-prong contacts 31') spaced outwardly from the board PCB beyond the row A.

The contact pieces are formed each of a body portion 3 or 3' located partly within a transverse slot in the bar 2, and a tongue portion 3a or 3b which extends from one end of the body portion beyond the lower face 2b of the bar 2. The prong portions are identical, except that the prong portions for the odd-numbered contact pieces 3 are arranged in a row A spaced a slight distance from the face of the panel, while the prong portions of the even-numbered contact pieces 3' are formed in positions to be aligned in a second row B spaced outwardly of the first row from the face of the printed circuit panel PCB.

The shape or outline for the contact pieces 3 for the inner row A is shown in heavy lines in FIGURE 4, while the shape or outline of the contact pieces 3' for the outer row B is shown in heavy lines in FIGURE 2..

For the purpose of retaining the contact pieces within the transverse slots 2e in bar 2, each piece is provided with a tab extension (3'0 in FIG. 2 and 3c in FIG. 4) on its outer edge and in a position to extend through the aperture 2e and into the groove 2d, with the end of the tab bent over from the dotted line position and into flat engagement with the bottom wall of the groove 2d. As shown in FIGURE 1, the tabs 3c and 3'0 for alternate contact pieces are staggered so that they are located on opposite sides of the center of the groove 2d.

The contact assembly is mounted upon the printed circuit board PCB by means of tabs 3d and 3'd formed on the outer side edge of the body portions of the contact pieces and extending into holes or apertures formed in the board. While only one securing tab is necessary, it is preferred to use two tabs on each contact piece, and to stagger the two tabs on adjacent pieces, so that the mounting tabs on the contacts in the assembly are arranged in four different rows as shown in FIGURES 2 and 4.

The tabs may be fastened within the receiving holes or sockets in the board in various ways, but it is preferred to form each mounting tab as a split finger, by splitting the tab along the middle as shown in FIGURES 2 and 4. The component prongs of the split-tabs are bent or bowed in opposite directions transversely of the plane of the body of the contact piece, 3 as shown in FIGURE 3, so that each tab is effectively enlarged at its mid portion by the oppositely bowed mid portions 3d and 3d" of the component prongs. As shown in FIGURE 3, the half-tab portion 3d is bowed to the left and the other half-tab portion 3d" is bowed to the right. The ends of of the two half-tab prongs remain in the same plane as the body portion of the contact piece as shown in FIG- URE 3. When the split tabs are inserted into the mounting holes in the board PCB the bowed portions 3d and 3d" will be pressed inwardly by the edges of the mounting holes, and, by using the proper size of mounting holes the bowed portions will engage the edges of the holes with suflicient pressure to retain the contact pieces securely mounted on the board and in contact with printed circuit strips PS carried by the board.

To provide for making a wire connection to the contact pieces, independently of any connection through printed strips PS, each piece may be provided with a tail extension on the upper side of the bar 2 and each extension is perforated to receive the end of a connecting wire. This is shown in FIGURES 2 and 4 where the square holes 3'e and 3e are formed in the tail extensions of contact pieces 3 and 3, respectively.

The groove 2d formed in the face 2d of bar 2 is sulficiently deep so that the ends of tabs 30 and 3'0 when bent over, as in solid lines in FIGS. 1 and 2, are located below plane of the bar face 2d, and the side walls of the groove protect the tabs from being short-circuited by conducting parts which may accidentally bridge the bar face 2d. It should be noted that the bar 2 remains in position on the contact pieces after they have been mounted upon the printed circuit board, and the bar functions to hold the contact pieces against lateral displacement from their correct positions for engagement with mating contacts in a connector socket. Each contact piece has a portion thereof (the tabs 3'0 and 3c in the present embodiment) which mechanically interlocks with the bar 2 and positively retains the pieces on the bar.

By using the split-finger tabs for mounting the contact pieces on the printed circuit board, all machining operations are performed at the time the contact pieces are made, and it is not necessary to stake the tabs to the board as in prior practice. Thus, the likelihood of cracking or splitting the board by a staking operation is avoided.

We claim:

1. A contact assembly for mounting upon printed cir cu-it boards comprising, an elongated bar of insulating material having transverse slots formed in one face thereof at spaced points along its length, a plurality of contact pieces formed of sheet metal stock mounted in said transverse slots, each contact piece having a portion thereof which is mechanically interlocked with said bar to prevent its removal from the slot in which it is mounted, each contact piece having a contact portion extending out of one end of the slot in which it is mounted and having a mounting tab extending away from said bar at right angles to said contact portion, said interlocking portion of each contact piece comprising a tab extension formed on the edge thereof located within its slot, said bar having apertures connecting the bottom of each slot through an opening in the face thereof opposite to the slotted face of the bar, said tab extensions extending through said apertures and openings and having the ends thereof deformed to prevent removal of the tabs from said apertures.

2. A contact assembly according to claim 1 wherein said bar has a shallow groove formed longitudinally thereof and in the face thereof opposite its slotted face, and said apertures open through the bottom of said groove, the ends of said tab extensions being bent over in said groove and lying Within the plane of the outer faces of the side Walls of said groove.

3. A contact piece for mounting upon a printed circuit board comprising a piece of sheet metal stock having a body portion and a prong portion extending from one edge of the body portion, and a mounting tab formed of a single-thickness integral extension of said body portion extending outwardly from another edge portion thereof, said tab being split lengthwise to form two half-tab prongs, said prongs having their mid-portions bowed out of the plane of said body portion in opposite directions.

4. A contact assembly for mounting upon printed circuit boards comprising, an elongated bar of insulating material having transverse slots formed in one face thereof at spaced points along its length, a plurality of contact pieces formed of sheet metal stock mounted in said transverse slots, each contact piece having a portion thereof which is mechanically interlocked with said bar to prevent its removal from the slot in which it is mounted, each contact piece having a contact portion extending out of one end of the slot in which it is mounted and having a mounting tab extending away from said bar at right angles to said contact portion, each mounting tab for each contact piece being formed on the edge thereof opposite to the edge mounted in said slots, and a mounting board having apertures formed therein receiving said mounting tabs, said mounting tabs comprising split-fingers having end portions of the component prongs thereof bowed in opposite directions to form an enlarged section on each mounting tab, the component prongs of said split-finger exerting outward resilient pressure on the edges of the mounting holes in said board and serving to hold said contact pieces securely in contact with the face of the board.

5. An assembly according to claim 4 wherein each of said contact pieces has a contact prong portion extending from one edge thereof parallel with the face of said board and an apertured tail portion extending from the Opposite edge of said contact piece.

References Cited by the Examiner OTHER REFERENCES Ruehlemann, H. E., Electronic Industries and Tele- Tech, October 1956, pages 62, 159 and 160.

JOSEPH D. SEERS, Primary Examiner. 

